1. Field of the Invention
The present invention relates to a modified regenerated cellulose fiber containing a grounder of naphthol dye, which can be dyed by treating it with a developer of naphthol dye when it is used alone or as a mixed yarn or union knitted/woven fabric, and enables dyeing melange yarn or union knitted/woven fabric in different colors, and also relates to dyed fiber products thereof.
2. Description of Related Art
It is well known that a dyeing method for cellulose-based fiber using a naphthol dye is one in which two kinds of dye intermediates composed of a grounder and a developer are absorbed in cellulose-based fiber in a solubilized state, separately followed by reacting to form water insoluble azo dyes on cellulose-based fiber, and that various hues can be obtained depending on combinations of a grounder (naphthol ASs) and a developer (bases, salts).
Naphthol dye has the features that it can provide a vivid hue mainly in reddish color and a deep color with a high fastness. While reactive dyes are mainly used for cellulose-based fiber, naphthol dyes are also used especially for a deep color with reddish hue. However, a dyeing process using naphthol dye is much more complicated compared with that using a reactive dye or the like. In the dyeing process using a naphthol dye, in order to dissolve a grounder (naphthol ASs) which is insoluble in water, it is necessary to make the grounder mud-like by adding a surfactant such as Turkey red oil or a dissolving agent such as ethanol, which is then dissolved carefully in a large amount of hot aqueous solution of sodium hydroxide. Since this process requires great skills in using an alkaline solution and controlling the pH and also has diversified steps depending on which of the bases or salts are selected as a developer to be used in the subsequent step, it is difficult to secure skilled dyeing workers. Thus, an improvement of this process has been required.
Spinning of a spinning solution mixed with a solid substance such as titanium oxide has been conventionally carried out. However, in the case of a spinning solution containing a liquid substance, the liquid substance is thought to flow out into the spinning bath. The present inventor has noticed that a solution of grounder of naphthol dye can be added and mixed into a spinning solution because the spinning solution in a viscose process or a cuprammonium process is alkaline, and that the flowing out of the grounder into the spinning bath is little, and thus completed the present invention.